An existing impairment of radio frequency over glass (RFoG) communication channels is Optical Beat Interference (OBI), which afflicts traditional RFoG networks. OBI occurs when two or more reverse path transmitters are powered on, and are very close in wavelength to each other. OBI limits upstream traffic, but also can limit downstream traffic. Existing efforts at mitigating OBI include adjusting ONUs to be wavelength specific, creating an RFoG-aware scheduler in the CMTS, changing ONU wavelengths in real-time, or combining multiple upstream inputs nominally in the same wavelength range.
However, such solutions for reducing or eliminating OBI require additional power. For example, to combine multiple upstream inputs nominally in the same wavelength range without the occurrence of OBI requires power to drive the photodiodes and the retransmitting laser. Some OBI reducing/eliminating devices have optical amplifiers, such as EDFAs, to aid in downstream splitting, which also requires additional power.
While distributed OBI free combining may result from employing a four-port combiner followed by four eight-port combiners and daisy chaining them together, such solution requires power to be provided at five spots (as opposed to power in just one spot with a thirty-two port combiner). The increased need for power is in contrast to the concept of FTTH, which is expected to be more passive and less reliant on powering. An exponential increase in power points is perceived as a reliability weakness in FTTH deployments, increases expenses, may not accommodate currently implemented splitting networks well, and may work well only in greenfield applications where the power system is laid simultaneously with the fiber network.
Improved techniques for reducing distortions in a network without the existing needs for increased power are desirable.
It is noted that while the accompanying Figures serve to illustrate embodiments of concepts that include the claimed invention, and explain various principles and advantages of those embodiments, the concepts displayed are not necessary to understand the embodiments of the present invention, as the details depicted in the Figures would be readily apparent to those of ordinary skill in the art having the benefit of the description herein.